The present application claims the benefit of the filing date of Canadian patent no. 2,357,533, filed Aug. 29, 2001.
The present invention relates to the field of providing gas drive to mechanical devices such as pumps and injectors at well-heads, using pressurized gas in a pipeline system, without the necessity of flaring or venting xe2x80x9cspentxe2x80x9d gas.
In particular, the present invention relates to a linear gas-driven system powered by pressure differential from produced gas to well-head gas without venting the gas spent or used in driving the system.
The invention has particular application (but is not thereby limited) in the field of gas production in the oil and gas industry, where it is often useful to provide power to energize well production equipment without resorting to externally (or remotely) supplied energy sources such as electrical power, and without using produced gas in internal combustion or other power-generating engines where waste products, heat, and maintenance are issues. The gas used is recirculated to the production line; the system is in that way a closed system.
It is well known to provide for generation of mechanical power (such as powered reciprocal motion by reciprocating piston/cylinder/valve means or rotary motion by turbine, fan, or combined reciprocal piston/crank means) utilizing pressure differentials between produced gas well-head pressure and atmosphere; likewise between produced well-head gas pressures and sales line pressures. Engines in which power is derived from partially expanding pressurized fluid to drive an output shaft are generally preferred over internal combustion. See U.S. Pat. No. 3,801,230, U.S. Pat. No. 4,369,373, U.S. Pat. No. 4,896,505, and U.S. Pat. No. 6,113,357, which each provide means of harnessing either fluid flow or differential pressure to provide mechanically available power for other purposes.
The use of valves and pistons in combination with a fluid operated pressure-powered system is also known. See patents U.S. Pat. No. 4,439,114 and U.S. Pat. No. 4,616,981, which describe the use of pistons in combination with valves and fluid pressure in a pumping system.
It is also well known to provide for the injection of chemicals into a well bore to assist in the production of desired hydrocarbons or the protection of the well""s equipment. See, for example, patents U.S. Pat. No. 3,901,313 and U.S. Pat. No.4,776,775. Of course, the injection of material into a well (which is typically at higher than atmospheric pressure) requires the use of mechanical or pressure-providing power sources.
It is known in the art that such power sources may be provided by the use of pressure-differential between well-head produced gas pressures and atmosphere, with the spent gas (that is, once it is relieved to atmospheric pressures after powering the devices required) being released to atmosphere or flared. At current prices for hydrocarbons, in particular natural gases, and with current constraints on pollution of the atmosphere, these techniques are not ideally suited for today""s use.
Engines that derive power from partially expanding pressurized fluid to drive equipment are preferred over internal combustion engines because of the absence of the involvement of volatile combustible fluids and the resulting exhaust gas which gives rise to pollution and safety concerns.
Several innovations have arisen due to those problems, such as the devices offered for sale and installation by ABI Oil Tools e-tronics Corp. under the trade name xe2x80x9cZero Emission Blair Air Systemxe2x80x9d, which powers a traditional venting glycol pump replacement with a closed-loop system in a containment device, depending upon the differential between well-head pressures and sales line pressures, which may be very high pressures, and may be very different pressures, and may be pressurized gases including corrosive or dangerous substances the release of which at high pressures could be problematic.
Another example of a similar containment device system is provided by the xe2x80x9cEnviro Drivexe2x80x94the Environmental Alternativexe2x80x9d system, which is a similarly powered, closed loop (that is, no escaping gases), production-to-sales line pressure-drop-driven injection pump (see xe2x80x9cenvirodrive.comxe2x80x9d web page as of Mar. 1, 2001).
It is therefore desirable to provide a source to energize equipment at the well-head in the form of reciprocating motion without venting or flaring exhaust gas. It is further desirable to provide such energizing motion without use of internal or other combustion of produced gas or fluids and without resort to externally provided power sources such as electricity, and without expensive external containment devices.
It is an object of this invention to overcome limitations in the prior art using internal or external combustion of fuel or sweet gas to drive pumps and to address safety and environmental issues related to such use. The existing prior art inadequately addresses the need for a recirculating linear gas drive system that utilizes pressurized gas, a simple closed valve and a piston drive system to drive a mechanical device, such as a pump, and that eliminates the need to routinely flare or release xe2x80x9cspentxe2x80x9d gas to atmosphere. None of the prior art discloses an invention that utilizes pressurized gas from a pipeline well-head, which is directed through a switching valve to drive a power unit with a piston to operate a pump.
This Invention relates to a system for providing drive to a mechanical well-head device by utilizing pressurized gas existing in a pipeline to power a unit containing a piston. This system provides for the use of pressurized gas within a pipeline system to provide gas drive to mechanical devices.
The invention is a system comprising:
produced gas;
a pipeline with gas at a lower pressure;
a manifold with flow control valve;
a reciprocating power unit;
a drive connection from power unit to a powered unit; and
a flow-directing switching means which, in time with the drive""s reciprocating movement to the end-point positions, switches communication of produced gas and pipeline with the appropriate sides of the power unit which returns spent gas to the pipeline
In particular, this invention in one embodiment is a system that provides the gas drive to a device using the pressurized gas in a pipeline, such as from the well-head, by directing that gas through a switching valve to a power unit containing a piston within a cylinder. The pressurized gas works against the piston, driving it through the length of the cylinder. When the piston reaches the end of the stroke, the switching valve reverses the flow in the valve manifold, so that the piston is driven back in the opposite direction. At the end of the reverse stroke, the switching valve changes the flow direction and drives the piston forward to the end of the stroke. This process may be continuously maintained by an adjustable flow control means, and may be turned on or off or have its speed or power varied by the flow control means.
The Invention has particular application (but is not thereby limited) in the field of gas production in the oil and gas industry, where it is often useful to provide power to energize well production equipment without resorting to externally (remotely) supplied energy sources such as electrical power, and without using produced gas in internal combustion or other power-generation engines where waste products, heat, and maintenance are issues. The use of pressurized gas also assists in preventing the system from stalling and will cure difficulties overcoming the friction of the driver.
These and other objects and advantages of the Invention are apparent in the following descriptions of the preferred embodiments of the Invention, which are not intended to limit in any way the scope or the claims of the Invention.